live-build/auto/config: don't repeatedly add the same pass name to the list of layers.

debian/changelog

@@ -1,3 +1,10 @@
+livecd-rootfs (24.04.19) UNRELEASED; urgency=medium
+
+  * live-build/auto/config: don't repeatedly add the same pass name to the
+    list of layers.
+
+ -- Steve Langasek <steve.langasek@ubuntu.com>  Thu, 18 Jan 2024 11:02:55 -0800
+
 livecd-rootfs (24.04.18) noble; urgency=medium
 
   * update apparmor feature overlay match for target 6.6 kernel.

live-build/auto/config

@@ -107,6 +107,12 @@ _register_pass () {
 	# $1 Name of the pass
 	[ "$PASSES_TO_LAYERS" != "true" ] && return
 
+	case "$PASSES" in
+		*$1*)
+			return
+			;;
+	esac
+
 	# live-build/ubuntu/hooks/020-ubuntu-live.chroot_early assumes the
 	# layer ending in '.live' is THE live layer to use, so ensure that
 	# we only define a single layer ending in '.live'.  It principle it